def p(n):
    for i in range(2,n):
        if n % i == 0:
            return False
    return True

x = []
j = ['one','two','three','four','five','six','seven','eight','nine',]
a = input()
a = a.split()
if len(a)<3 or a[0] not  in j or a[1] not  in j or a[2]  not  in j:
    print("Wrong input")
else:
    for i in a:
        if i=='one':
            x.append('1')
        if i=='two':
            x.append('2')
        if i=='three':
            x.append('3')
        if i=='four':
            x.append('4')
        if i=='five':
            x.append('5')
        if i=='six':
            x.append('6')
        if i=='seven':
            x.append('7')
        if i=='eight':
            x.append('8')
        if i=='nine':
            x.append('9')
    s=''.join(x)
    prost=[]
    for i in range(2,1500):
        if p(i):
            prost.append(i)
    mn=10000
    k = 0
    for i in prost:
        if abs(i-int(s))<mn:
            mn = abs(i-int(s))
            k=i
    print(k)
